X-Ray Reflection Nebulae with Large Equivalent Widths of Neutral Iron Ka Line in the Sgr C Region

TL;DR

This study presents Suzaku observations of the Sgr C region, identifying four diffuse X-ray clumps with strong neutral iron line emission, indicating they are X-ray reflection nebulae, and reports the discovery of a new clump.

Contribution

First Suzaku detection of four diffuse Fe Kα clumps in Sgr C, including a newly discovered one, with analysis supporting their origin as X-ray reflection nebulae.

Findings

Detected four diffuse Fe Kα clumps with large equivalent widths.

Identified a new X-ray reflection nebula in Sgr C.

Confirmed the reflection origin through spectral analysis.

Abstract

This paper reports on the first results of the Suzaku observation in the Sgr C region. We detected four diffuse clumps with strong line emission at 6.4keV, Ka from neutral or low-ionized Fe. One of them, M359.38-0.00, is newly discovered with Suzaku. The X-ray spectra of the two bright clumps, M359.43-0.07 and M359.47-0.15, after subtracting the Galactic center diffuse X-ray emission (GCDX), exhibit strong Ka line from FeI with large equivalent widths (EWs) of 2.0-2.2keV and clear Kb of FeI. The GCDX in the Sgr C region is composed of the 6.4keV- and 6.7keV-associated components. These are phenomenologically decomposed by taking relations between EWs of the 6.4keV and 6.7keV lines. Then the former EWs against the associated continuum in the bright clump regions are estimated to be 2.4(+2.3_-0.7)keV. Since the two different approaches give similar large EWs of 2keV, we strongly suggest that the 6.4keV clumps in the Sgr C region are due to X-ray reflection/fluorescence (the X-ray reflection nebulae).